Fluorine crustal abundance

In the geosphere, strontium is ranked fifteenth in the order of the elemental crustal abundance at 450 ppm. Its presence is greater than that of carbon or chlorine, and slightly less than that of sulfur or fluorine. Of the trace elements, it is ranked fifth [7). Strontium is mainly found in Scotland and the United States, where calcareous rocks with natural apatites containing up to 73000 ppm of strontium are located [8]. 

Fluorine is the thirteenth element in order of abundance in crustal rocks of the earth, occurring to the extent of 544 ppm (cf. twelfth Mn, 1060 ppm fourteenth Ba, 390 ppm fifteenth Sr, 384 ppm). The three most important minerals are... 

Bromine is substantially less abundant in crustal rocks than either fluorine or chlorine at 2.5 ppm it is forty-sixth in order of abundance being similar to Hf 2.8, Cs 2.6, U 2.3, Eu 2.1 and Sn 2.1 ppm. Like chlorine, the largest natural source of bromine is the oceans, which contain 6.5 x 10 %, i.e. 65 ppm or 65mg/l. The mass ratio Cl Br is 300 1 in the oceans, corresponding to an atomic ratio... 

Bromine is substantially less abundant in crustal rocks than either fluorine or chlorine at... 

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